The instant invention falls in the field of marine propulsion systems that utilize enclosed powered rotors that accelerate water or fluids taken from external to a marine vehicle to thereby generate a propelling thrust. They are commonly known as waterjet propulsors. In commercially available state-of-the-art waterjet propulsors a powered rotor or impeller builds up a pressure in water forward of a discharge nozzle that discharges to atmosphere. The differential pressure across the discharge nozzle results in a jet velocity that, when discounted for incoming water picked up at marine vehicle velocity and multiplied by the mass flow of water, gives the resulting thrust.
Several shortcomings of the present day waterjets are evident: 1) Since they have impellers that are basically simple water pressurizing pump impellers, they have a serious falloff in performance when air is ingested as is the case when operating in rough seas and/or when propelling air cushioned marine vehicles, 2) They are subject to impeller blade cavitation damage especially when running at high power levels at low marine vehicle speeds, 3) Their efficiencies at low marine vehicle speeds is generally considered to be poor with speeds of 35 knots or more considered necessary for optimum performance, 4) Their performance at very high marine vehicle speeds, say over 55 knots or so, is also poor due mainly to low efficiency of and high drag of their water inlets at the higher speeds, and 5) In multiple unit installations, drag of a non-operating waterjet is of a high magnitude due to water passing through the non-operating waterjet. In spite of all of their drawbacks, present day waterjets are seeing a lot of applications. These are primarily in craft that cruise mostly in the 35-50 knot area such as high speed ferries where their advantages of low maintenance and even engine loadings compared to open water propellers is valuable. They are also seeing application in small jetboats and personal watercraft where the loss of efficiency compared to the open water propeller is accepted for the added safety considerations of the enclosed rotor.
Presented here are some new concepts in a waterjet propulsor that solve all of the present-day waterjets just mentioned shortcomings. They are mainly improvements on a newer variation of a waterjet propulsor that uses a rotor that is supplied with gas over part of its rotation during it primary mode of operation. The basic ideas of this new type of propulsion system are given in Applicant""s earlier U.S. Pat. Nos. 5,505,639, 5,730,636, and 6,024,614.
The instant invention waterjet propulsor not only supplies gas to its fluid-accelerating rotor during forward high speed propelling of a marine vehicle but also has a simple way to prevent gas from reaching the rotor when operating at low speed or during reversing. Preventing gas from reaching the rotor during low speed operation insures that the mass flow is about doubled which enhances thrust at low marine vehicle speeds. Also, it is particularly important to be able to prevent gas from reaching the rotor during reversing. This is because when the rotor is trying to build up pressure to impact a reversing bucket it tends to spin freely in a gas pocket if gas is entrained in the water. Little reversing thrust is generated in such a case. Lastly, an adjustable inlet fluid device can direct inlet water away from its water inlet to reduce drag of a non-operating unit.
With the foregoing in mind, it is a principal object of present invention to provide a new enclosed fluid accelerating rotor marine vehicle propulsion system that has an enclosed fluid accelerating rotor that is capable of operating efficiently when either partially or fully submerged in water.
It is a further related object of the invention that its inlet be a ram fluid inlet, as seen in vertical transverse planes of the improved waterjet propulsor with a rotational centerline of the fluid accelerating rotor horizontal, to thereby be, as a sum of its parts, a ram fluid inlet over a majority of 180 degrees of an arc.
It is yet another object of the invention that said ram fluid inlet be, at least in its majority, disposed above a lower portion of the marine vehicle forward of the ram fluid inlet.
Another object of the invention is that an adjustable inlet fluid directing means be disposed, at least in its majority, forward of said ram fluid inlet.
A further object of the invention is that it include a gas supply means that is capable of supplying gas to a forward portion of the fluid-accelerating rotor.
It is another object of the invention that the ram fluid inlet, on average, angles rearward from its upper to lower portions.
It is a further directly related object of the invention that the ram fluid inlet, on average, angle rearward from its upper to its lower portions at an angle of less than 60 degrees to a transverse horizontal plane of the improved waterjet propulsor when a rotational centerline of said fluid accelerating rotor is horizontal.
It is yet another directly related object of the invention that the ram fluid inlet, on average, angles rearward from its upper to its lower portions at an angle of less than 50 degrees to a transverse horizontal plane of the improved waterjet propulsor when a rotational centerline of said fluid accelerating rotor is horizontal.
A further directly related object of the invention is that the ram fluid inlet, on average, can angle rearward from its upper to its lower portions at an angle of less than 40 degrees to a transverse horizontal plane of the improved waterjet propulsor when a rotational centerline of said fluid accelerating rotor is horizontal.
Yet another object of the invention is that an inlet lip of said ram fluid inlet can be, at least in part, angled downward by an angle of less than twenty degrees to a transverse horizontal plane of the improved waterjet propulsor when a rotational centerline of said fluid accelerating rotor is horizontal.
A further refinement of the just mentioned object of the instant invention is that an inlet lip of said ram fluid inlet can be, at least in part, angled downward by an angle of less than fifteen degrees to a transverse horizontal plane of the improved waterjet propulsor when a rotational centerline of said fluid accelerating rotor is horizontal.
Yet another refinement to the just mentioned objects of the instant invention is that an inlet lip of said ram fluid inlet is, at least in part, angled downward by an angle of less than ten degrees to a transverse horizontal plane of the improved waterjet propulsor when a rotational centerline of said fluid accelerating rotor is horizontal.
It is still a further object of the invention that said ram fluid inlet is, at least in its majority, disposed below a rotational centerline of the fluid-accelerating rotor.
Another related object of the instant invention is that the ram fluid inlet is, at least in its majority, curvilinear in shape.
Yet another object of the invention is that an adjustable inlet fluid directing means can, when the marine is vehicle moving forward, direct a majority of incoming water away from impacting the ram fluid inlet.
A further object of the invention is that, when the marine vehicle is moving forward, an adjustable inlet fluid directing means can direct a majority of incoming water to the ram fluid inlet.
A related object of the instant invention is that the adjustable inlet fluid directing means can direct incoming water to at least a majority of an inlet of said fluid accelerating rotor.
It is a further object of the invention that the adjustable inlet fluid directing means can be composed of two or more fluid directing elements wherein said fluid directing elements are moveable in relation to the improved waterjet propulsor.
It is another object of the instant invention that movement of at least one of the fluid level directing elements is accomplished by forces supplied by an actuator.
It is a further object of the invention that one of said inlet fluid directing elements is a port inlet fluid directing element and another is a starboard inlet fluid directing element.
It is a directly related object of the present invention that it further include a center fluid-directing element that can be actuated by contact with the port or the starboard fluid-directing element.
It is yet a further object of the invention that a gas inlet of the gas supply means capable of supplying gas to the fluid accelerating rotor is, at least in its majority, above a waterline when the improved waterjet propulsor is generating forward thrust thereby supplying gas to a forward portion of the fluid accelerating rotor and submerged below a waterline when the improved waterjet propulsor is generating reverse thrust thereby supplying water to the fluid accelerating rotor.
It is a further object of the invention that the fluid-accelerating rotor rotates in the same direction when the improved waterjet propulsor is generating forward thrust as when it is generating reverse thrust.
It is yet another object of the invention that a gas inlet that supplies gas to the fluid accelerating rotor during forward operation of the marine vehicle is, at least in its majority, submerged below a waterline during reverse operation of the marine vehicle.
Yet another object of the invention is that it further comprise a steering rudder disposed, at least in its majority, aft of the fluid accelerating rotor and forward of a multi-element fluid reversing bucket.
A directly related object of the invention is that a housing portion forward of said steering rudder is, at least in its majority as seen in a vertical transverse plane of the improved waterjet propulsor, internally curvilinear in shape and a forward portion of said steering rudder, as seen in a profile view, is curvilinear in shape such that rotation of the steering rudder causes a biased sideways directing of fluid flow during reverse thrust operation of the improved waterjet propulsor.
It is an another object of the present invention that a housing portion forward of said steering rudder can be, at least partially as seen in a vertical transverse plane of the improved waterjet propulsor, internally rectangular in shape over an upper portion and curvilinear in shape over a lower portion and a forward portion of said steering rudder, as seen in a profile view, is rectangular in shape over an upper portion and curvilinear in shape over a lower portion such that rotation of the steering rudder causes a biased sideways directing of fluid flow during reverse thrust operation of the improved waterjet propulsor.
It is a further related object of the instant invention that the multi-element fluid-reversing bucket comprises an element that is in mechanical communication with reverse fluid flow directing nozzles.
A related object of the invention is that power for movement of a first element of said multi-element fluid reversing bucket is provided by an actuator and wherein movement of said first element of said multi-element fluid reversing bucket results in movement of an adjacent second element of said multi-element fluid reversing bucket.
A further and directly related object of the invention is that movement the second element of said multi-element fluid reversing bucket results in movement of an adjacent third element of said multi-element fluid reversing bucket.
A related object of the present invention is that an aft portion of the steering rudder is, at least during portions of its operation during reversing of the improved waterjet propulsor, in close proximity to an element of the fluid-reversing bucket.
Yet another object of the instant invention is that it may have a flush fluid inlet.
A directly related object of the invention is that the flush fluid inlet may be accompanied by an adjustable inlet fluid directing means disposed, at least in its majority, forward of said flush fluid inlet and wherein said adjustable fluid directing means is capable of directing incoming water away from said flush fluid inlet.
The invention will be better understood upon reference to the drawings and detailed description of the invention which follow in which: